Dear Goutham Sajja ,

Since the inductance L of the solenoid is proportional to the permeability of the core material then define an average for the permeability of the core as follwing:

Assuming the core length is l, the total length of the gap is lg and the plunger movement stroke=x,

Then u average= {(l - lg +x) u + (lg-x) u0}/ l

In this way you can get L as a function of x, the displacement of the plunger from the rest position.

Best wishes

Dear Goutham Sajja,

I suggest you to see links and attached file on topic.

https://www.mdpi.com/1424-8220/18/12/4492

https://www.robocup2017.org/file/symposium/RoboCup_Symposium_2017_paper_30.pdf

https://etd.ohiolink.edu/apexprod/rws_etd/send_file/send?accession=wright1284684673&disposition=inline

http://web.mit.edu/8.02t/www/802TEAL3D/visualizations/coursenotes/modules/guide09.pdf

Best regards

Dear Goutham Sajja ,

Since the inductance L of the solenoid is proportional to the permeability of the core material then define an average for the permeability of the core as follwing:

Assuming the core length is l, the total length of the gap is lg and the plunger movement stroke=x,

Then u average= {(l - lg +x) u + (lg-x) u0}/ l

In this way you can get L as a function of x, the displacement of the plunger from the rest position.

Best wishes

Dear Sir,

I thank you for your valuable reply. I really appreciate it. With the help of the formula that you have suggested, I can certainly calculate inductance of the solenoid as a function of the displacement of the plunger.

As the current is supplied to the solenoid, the plunger begins to move towards the center. In the completely engaged position, I know the current that is drawn by the solenoid from the data sheet of the solenoid. But initially after the current is supplied, when the plunger is at rest with an air gap of 3 mm between the core and the plunger, will the value of the current drawn by the solenoid be different than when the plunger is in the completely engaged position.

I plan to use the following formula to calculate the current drawn by the solenoid coil: i = (1/L)*int(v-i*(dL/dx)*(dx/dt)) where i = current in the solenoid coil v = voltage L = inductance of the solenoid dL/dt is split into (dL/dx)*(dx/dt)

In this formula I know the value of L at each step of the plunger movement x. I plan to use a motion sensor block available in simulink through which I can obtain dx/dt. But can you please comment on how to evaluate the value of dL/dx

Thanks and Best Regards, Goutham Sajja

Dear Abdelhalim abdelnaby Zekry , regarding the formula that you initially suggested to evaluate L as a function of x, which is

u avg = {(l - lg +x) u + (lg-x) u0}/ l

I have found another method of evaluating L as a function of x. I kindly request you to give your inputs on that.

From the experimental results, I know the value of force stroke data. So with the help of the relation:

F*dx = 0.5*i^2*dL

where F = force available, dx = steps of plunger movement, dL = rate of change of inductance, i = value of current

I can evaluate dL/dx from the above relation. Further, if I integrate dL/dx, I can get L as a function of x.

I kindly request you to comment on this approach.

Thanks and Regards,

Goutham Sajja